Advertisers and merchants desire the ability to display graphic images on a wide variety of surfaces. In recent years, transparent surfaces such as windows, glass partitions (as found in shopping malls), and the like have attracted a great deal of attention as substrates for advertising media.
In certain applications, if a graphic article is applied to a transparent substrate, such as a window, it is desirable that the image be visible when viewed from one side of the window, while leaving the window and image substantially transparent when viewed from the other side of the window. For example, if the image is to be mounted on a window of a vehicle, such as a bus or taxicab, it is desired that passengers be able to see clearly through the window, while pedestrians outside of the vehicle see the graphic images.
In other applications, if a graphic article is applied to a transparent substrate, it is desirable that the viewer be able to see the image as well as objects beyond the substrate. For example, in such structures as banks where security is of importance, not being able to see out through the windows can present serious security problems, endangering the wellbeing of the bank customers and employees. Therefore, if the image is to be mounted on a window of a bank, it is desired that the bank customers inside the bank be able to see the advertising or promotional image, while bank employees (or security personnel) inside the bank be able to see clearly through the window.
Other applications may include applying two images to both sides of a laminate—one on each side—to be applied to a transparent substrate, where the first image is visible from one side of the substrate and not the other, and the second image is visible from the other side but not the first, while the viewer can still see through the substrate from either side.
Graphic articles achieving these visual effects typically are multi-layer film constructions with a light-colored, opaque film adapted to receive an image on one surface and a dark, light-absorbing film on the opposite surface. Numerous perforations through the film layers create an optical illusion of “transparency” through the graphic article.
In a unidirectional application, the multi-layer film constructions are stacked and the perforations are sized and spaced such that, when observed from the imaged side, a viewer has a tendency to focus on the image; however, when observed from the other side, the viewer has a tendency to see through the graphic article, leaving the window unobstructed.
In the see-through applications, the multi-layer film constructions are stacked and the perforations are sized and spaced such that, when observed from the imaged side of a single-sided graphic article, or either side of a double-sided graphic article, a viewer has a tendency to focus on the image or look through the graphic article, leaving the window unobstructed.
In all cases, vision through the graphic article can be obtained in either direction when the level of illumination perceived through the graphic article from the far side of the graphic article sufficiently exceeds the illumination reflected from the near side of the graphic article.
U.S. Pat. No. 4,673,609, to Hill, discloses a method of painting one-way graphics onto windows by the use of a mask applied to the window where paint goes through the holes to adhere directly to the glass. There are many problems associated with this method:
1. If the mask does not adhere properly, the paint will bleed under the mask and create unsightly irregular or ragged patterns of dots.
2. Removal of the mask may remove portions of the color or lift entire dots from the surface of the glass.
3. Removal of the graphics from the glass is labor intensive, requiring the use of aggressive window cleaning techniques, and the washed off or scraped off paint particles can stain the surrounding areas such as window frames or sills, wall areas, landscaping and walkways.
5. Multiple coats of paint are required to achieve the one-way graphics: first a dark (usually black) coat is applied, and then after the black coat has dried, at least one coat of the background color is required to cover the black coating.
6. One-way graphics painted directly onto glass require a significant investment of time—both in the application of several coats of paint and in the labor-intensive removal methods required.
A considerable advance in respect of such conventional methods is represented by the teachings of U.S. Pat. No. 5,773,110, to Shields: a window to be provided with a display product is masked with masking paper. A perforated panel is cut to fit the window and attached over the masking paper. The perforated panel is painted with an image that is desired. Once the painting is completed, the panel is taken away from the masking paper. The painted panel with the one or more layers of paint thereon is applied to the window. The perforated panel could have an adhesive coating that would have a protective backing liner to protect the adhesive. The perforated panel is peeled or separated from the backing masking paper, thus, leaving the holes of the perforated panel free as well as holes in the painted liner.
Problems comparable to the ones of Hill—even though less severe—exist with the teachings of Shields: if the adhesiveness of the masking paper used is potent, more paint than desired might be removed from the perforated panel (which has one or more layers of paint) while it is being peeled or separated from the backing masking paper. Alternatively, if the adhesiveness of the masking paper used is feeble, some of the holes of the perforated panel might not be freed during the peeling process.
Also, even though the method of Shields is less time consuming than Hill's, it is still desired to further improve on the time investment needed in the production of these graphic panels.
As can be readily seen, these methods of hand-painted graphics and other contemporary methods do not possess all of the desirable advantages required to adequately create unidirectional and see-through graphics. Thus, there is a need for a method for creating these graphics. The present invention satisfies that need.